sf

noun

By · According to Wiktionary data (CC BY-SA) ·

"sf" is a 2-letter English headword indexed on PlainSpell.

The verdict

“sf” sits in 20 confusable pairs (corpus #8,606) as a noun. The look-alike neighbours are the real trap.

#8,606
frequency rank, English
6,566
“S” headwords
20
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Alternative form of SF (science fiction)

Corpus desk

Index EN-sf · sf · English

sf · rank #8,606 · 0 variants · 20 confusables

  • FREQ-COMMON #8,606
  • LEN-SHORT 2 letters
  • VOW-0 0 vowels
  • CONFUS-HIGH 20 pairs
  • VAR-0 0 variants
  • BOOK-DENSE 6,566
  • PHOTO-FINISH shiny

Nearest frequency peer: shiny (+1 rank slots)

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Frequency neighbourhood for “sf”

Lower corpus rank = more everyday usage (inverted bar length for readability)

corpus weight

What this shows Bars show where “sf” sits against the nearest ranked English headwords in the FrequencyWords band, not a reprint of letter-browse containment.

Source FrequencyWords open word-frequency list As of September 3, 2026

Visual similarity to commonly confused words

How many letter changes separate each confused pair (Levenshtein distance, normalized).

sf vs so
50% similar
sf vs SI
0% similar
sf vs SS
0% similar

Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).

Key facts for sf
PropertyValue
Headwordsf
LanguageEnglish
Part of speechNoun
Letters2
Frequency rank#8,606
Misspellings tracked0
Confusable pairs20
SourceWiktionary (kaikki.org)

Where “sf” sits in English frequency

This scale runs from the tiny cluster of words that carry ordinary speech (left) to the long tail of words almost nobody reaches for (right).sf lands here:

#1#100#1K#10K#100K
← used constantlyrarely used →

Scale is logarithmic (each tick is 10× rarer). Source: FrequencyWords open word-frequency list.

Easy to mix with look-alikes

The spelling risk for sf is neighbouring look-alikes ("so", "SI", …), not just typos; it is anoun. Frequency #8,606 among 6,566 “S” headwords. 2 recorded senses keep meaning in play.

sf has no tracked misspelling variants, a straightforward case of a spelling with little room for common typos. It also participates in 20 confusable-pair relationships, "so", "SI", "SS", and more, where similar look or sound leads writers to substitute one word for another in context.

No explicit etymology string is stored for this entry, so its spelling pattern is best understood through pronunciation rather than a traceable origin. The correct English form is sf, spelled S-F.

Definition

  1. 1
    Alternative form of SF (science fiction)
  2. 2
    Abbreviation of significant figure(s).

Recorded use

Wiktionary example

These source excerpts show how sf appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. But some discussion of the complex relationship between “allohistory” and sf is appropriate here, as the genres overlap in certain ways. Classical allohistory— such as Trevelyan's "What if Napoleon had won the Battle of Waterloo?" and Churchill's "If Lee had not won the Battle of Gettysburg" —is a rigorously consistent thought-experiment in historical cau…

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

PlainSpell is rendered directly from structured Wiktionary extracts and open word-frequency lists, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of September 3, 2026. Primary sources: Wiktionary (via kaikki.org) and FrequencyWords.

Frequently Asked Questions

How do you spell "sf"?
"sf" is spelled S-F.
What does "sf" mean?
As a noun, "sf" means: Alternative form of SF (science fiction)
What words are commonly confused with "sf"?
"sf" is commonly confused with "so", "SI", "SS". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
What language does "sf" come from?
"sf" is a English word. PlainSpell's reference spans five languages -- English, Spanish, Portuguese, French, and German -- with definitions, pronunciations, and spelling data for each.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

What to do next

You've looked up "sf". Here's where to go from here.

  • "sf" maps to 20 confusable pairs in this vintage; the highest-scored is "so". View pair
  • Usage frequency rank #8,606 among English headwords in this corpus. Corpus statistics
  • Browse more English words in the "S" letter cohort. S–Z browse
  • PlainSpell rotates a curated Word of the Day from the English corpus, a passive way to discover vocabulary. Word of the Day

PlainSpell is a reference corpus, not spelling advice. Verify unusual forms in context.

Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list